用周期倍差法评价数据采集系统的传递函数

The Equivalent Sampling Period Method for the Identification and Evaluation of the Transfer Function of Data Acquisition Systems

数据采集系统传递函数的辨识和评价，是其总体性能评价中至关重要的一个目标，在此，首要的前提条件是其瞬态响应的获得。由于采样周期是有下限的，即采集速率不可能无限高，这在实际应用中常常限制了其瞬态响应特性的获得，因而也限制了其传递函数的辨识和评价。本文介绍一种方法，通过对其加载特定的周期性输入信号，使用采样周期的整数倍和信号周期整数倍间的微小偏差，获得比实际采样周期小得多的等效采样周期，从而解决了数据采集系统瞬态响应特性的获取问题；并进而获得了数据采集系统传递函数的辨识和评价结果，实现了数据采集系统瞬态特性的总体评价。

The identification and evaluation of the transfer function of Data Acquisition System(DAS)is very important in its overall evaluation,and its transient response is required for this purpose. Because of that there is a lowest limit of the sampling rates of each Data Acquisition System, that is the sampling rate can not be at any value (especially it can't be at any high enough), one can't get the transient performance of DAS sometimes,and it may limits the evaluation of their transient performance. We propose in this paper an evaluation method for the transient performance of DAS,through the period signal, by utilizing the much smaller difference than sampling period between the multi periods of signal and the multi sampling periods,getting shorter equivalent sampling period(i.e. higher equivalent sampling rate),which is derived from input signal period and sampling period,and then ,the problem that how to get the transient performance of DAS has been solved.The transfer function of DAS is then evaluated and identified,and practical test results are also presented.